Fuel injection pump for internal-combustion engines



June 5, 1951 e. PALUMBO FUEL INJECTION PUMP FOR INTERNAL-COMBUSTION ENGINES Filed May 6, 1949 FIG.1

Patented June 5, 1951 FUEL INJECTION PUME' FOR INTERNAL- CQMBUS TION' ENGINES Giuseppe;BalumbmEoggimItaly Application May 6', 1949", Serial No. 91,716 In Italy May 17', 1948 9 Claims. 1.

This" invention relates to improvements in injection pumps for internal combustioirengines, of the valve type as distinguished from slide valve pumps;

An object of this invention is to accommodate the valve in the cylinder head and actuate said valve by means of thepiston.

A' further object oi this invention is to. cause the valve'toconstantly bear on a boreddisc'which is: slidably' mounted within the piston and? is pressed'by' a spring.

Further objects of this invention will appear from the appended specification in which refer ence is" made to the accompanying drawing in which Fig. 1 is an axial cross section of a construction of myimproved injection pump, and Fig: 2 shows a detail.

On the-drawing I denotes the pump casing, 2 is the cylinder in which moves the piston 3 in the form of a case having its bottom turned downwardly.

A head" 4 is mounted at thetop-of'the cylinder and a valve 5 controlling the Diesel oilinlet. is slid'ably guided therein.

The valve 5 seals on its seat 6 formed in the head 4' in which it' is suitably guided for displacement and is pressed by a spring- 1 which tends to keep the valve open or'removed from its seat.-

The valve is formed with a tappet-shaped extension 31' abutting the top flat surface of the disc 8 which is mounted for displacement inthe internal cylindrical chamber of the piston- 3 and is pressed by a spring l enclosed in said cylindrical recess and tending tomaintain the disc 8 against an abutment in the form of a resilient ring' H.

l2 denotes a longitudinal inlet manifold for the oil which flows through the port l3, chamber l4, bores l5, chamber [-6 and radial holes l in the head 4 reaching underneath the valve 5.

When the piston 3 is in its lowest inoperative position, it abuts the topsurface of the cylinder 21' against; which the; piston is pushed by' the spring 1 of the valve on the last: portion. of( its inward stroke: when the spring l-IJ: would no longer be eifective on account of removal of the tappet 3| from the disc 8, further movement being checked by the ring H In this inoperative position of. the piston, the valve is not pressed by the spring Hi, and is merely acted upon by the small spring 1. The valve is therefore open, as shown on the drawmg.

Consequently, the oil flows through the valve to the recess above the piston 3' and through the bores I9 in the disc 8 to the inner chamber of thepiston 3, filling the latter and all otherabove described passages.

On lifting the piston 3 by any mechanical, hydraulic, electric or pneumatic means, the valve 1 isnow promptly loaded by the spring I I] which overcomes the weaker spring I and sharply closes the valve. As the piston is moved further upwards, the oil collected underneath the valve is pushed through the holes 20 in the head 4 towards the injectors on the engine.

The pump is of course provided on its pressure linewith the ordinary check valve and all other known devices which are neither described nor illustrated for the sake of simplicity.

Use of the pump according to this invention eliminates in the check valve the usual collar adapted to cause the drop in pressure, thereby eliminating the drawbacks deriving therefrom.

In the construction shown by way of example, the piston 3 of the fuel pump is operated by a hydraulic transmission. A cylinder 2| is arranged in the pump casing l underneath the cylinder 2 and a piston 22 moves in said cylinder. The piston 22- is of the usual type employed in injection pumps with the difference that the liquid pumped therebyis lubricating oil instead of Diesel oil.

2 3 denotes the usual suction and reflux holes in the cylinder 2| and 24 denotes the outer cylinder chamber, which communicates with the annular chamber 25 in the casing connected with the reservoir of the lubricating oil.

It will be obvious that by operating the piston 22 as in a conventional injection pump and by the usual adjusting means, a movement of the piston 3 will be transmitted by a hydraulic transmissioneffected by the lubricating oil, which will supply deliveries equal to those which would have been supplied by the piston 22 if it had pumped fuel oil as in ordinary pumps, while affording the advantage that the said piston 22 is practically of a longer life, the contact with fuel oil being eliminated.

The life of the piston 3 will also be increased over the normal life of the pistons of injection pumps, although it directly acts on the fuel oil, because the valve function is not performed by the piston, which results in well-known objectionable consequences, the said function being performed by the head valve 5.

In order to feed lubricating oil to the lower cylinder and. piston, an upper manifold 26 is provided which communicates through the cona tight seal between the fuel oil circulating above" the cylinder 2| and lubricating oil circulating underneath the top surface of said cylinder. Moreover, this resilient packing performs the above function without any risk of deformation of thecylinder 2 and ensuing sticking of the piston 3. The above described device may be suited for instance by the modification shown on the drawing for transforming conventional pumps for operation according to this invention.

In manufacture of new pumps according to this invention, the construction will be suitably varied without departing from the principle described.

What I claim is:

1. In a fuel injection pump for internal combustion engines, the combination with a cylinder, a hollow piston movable in said cylinder and a head forsaid cylinder, of a fuel inlet valve cooperating with a seat in said head and guided on its movement in an axial bore in said head, a weak spring between the bottom of said bore and said valve for maintaining the latter in its open position, a disc movable in said piston, a spring stronger than the firstmentioned spring between the disc and piston bottom for maintaining the disc against an abutment on the edge of the recess in the piston and an extension fixedly connected with said valve and bearing on said disc.

2. In a fuel injection pump for internal combustion engines, the combination with a cylinder, a hollow piston movable in said cylinder and head for said cylinder, of a fuel inlet valve cooperating with a seat in said head and, on the other side, an extension projecting into said cylinder, a weak spring between the bottom of said recess and the plunger tending to keep said valve in its open position, and a resilient member in said piston on which said extension bears.

3. In a fuel injection pump for internal combustion engines, the combination with a cylinder, a hollow piston movable in said cylinder and head for said cylinder, of a fuel inlet valve cooperating with a seat in said head and having,ion one side, a plunger guided in an axial recess in said head and, on the other side, an extension projecting into said cylinder, a weak spring between the bottom of said recess and the plunger tending to keep said valve in its open position, a disc movable in said piston and having holes for the flow of fuel, a spring stronger than the firstmentioned spring between the disc and piston bottom tending to push the said disc outwardly against the extension on said'valve.

4. In a fuel injection pump for internal combustion engines, the combination with a pump casing, pump cylinders in holes in said casing and a head for each of said cylinders, of an annular packing between said body and each of said cylinders held in position by said head, a fuel inlet valve cooperating with a seat in said head and guided on its movement in said head and a resilient member in said piston for closing said valve when said piston performs its pressure stroke.

5. In a fuel injection pump for internal combustion engines, the combination with a pump casing, of pump cylinders in holes in said casing, said cylinders having at one end an annular outer bearing flange of conical shape, a packing ring of resilient material bearing on the conical sur- "face of said flange between the cylinder and pump casing, a pressure disc on said packing ring, a

' coiled spring acting on said disc, a cylinder head adapted to load the spring, a fuel inlet valve cooperating with a seat in said head and guided on its movement in said head and a resilient member in said piston for closing said valve,

when said piston performs its pressure stroke. V

6. In a fuel injection pump for internal combustion engines, the combination with a cylinder, a hollow piston movable in said cylinder and a head for said cylinder, of a fuel inlet valve cooperating with a seat in said-head and guided on its movement in an axial bore in said head, a weak spring between the bottom of said bore and said valve for maintaining the latter in its open position, a disc movable in said piston, a spring stronger than the first-mentioned spring between the disc and piston bottom for maintaining the disc against an abutment on the edge of therecess in the piston and an extension fixedly connected with said valve and bearing on said disc, and means for actuating said piston against the action of said stronger spring.

'7. In afuel injection pump for internal combustion engines, the combination with a cylinder, a hollow piston movable in said cylinder and a head for said cylinder, of a fuel inlet valve cooperating with a seat in said head and guided on its movement in an axial bore in said head, a weak spring between the bottom of said bore and said valve for maintaining the latter in its open position, a disc movable in said piston, a spring stronger than the firstmentioned spring between the disc and piston bottom for maintaining the disc against an abutment on the edge of the recess in the piston and an extension fix edly connected with said valve and bearing on said disc, and hydraulic means for actuating said piston against the action of said spring.

: 8. Injection pump as claimed in claim '7, in

which the hydraulic means consists of a pump of which the cylinder freely communicates with REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date 4 2,313,264 Reggio Mar. 9, 1943 2,378,165 Waeber June 12, 1945 2,389,492

Edwards Nov. 20, 1945 

